Hi Reeka,
Yes you can turn back at will. However, I have noticed mention of a bug in the game that sometimes when you turn into Slayer you die instantly. You may just want to save a game and try it and see if this bug is in your game, it wasn't in mine?!?! Also, you lose 2 reputation points everytime you turn into slayer, so it should only be used as a last-ditch effort. Hope this helps.
(no i'm not back, just answering a few game questions when I can
)
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It is better to keep your mouth shut and appear ignorant,
than open it and remove all doubt!